Strap-stretching device



Dec. 9, 1930.

R. H. NORTON 1,784,025

STRAP STRETCHING DEVICE Filed May 10, 1928 3 Sheets-Sheet l -Dec. 9, 1930. R. H. NORTON STRAP STRETCHING DEVICE Filed May 10, 1928 3 Sheets-Sheet 2 Dec. 9, 1930. R. H. NORTON STRAP STRETCHING DEVICE Filed May 10, 1928 3 Sheets-Sheet 3 Patented Dec. 9, 1930 UNITED STATES PATENT OFFICE RALPH H. NORTON, OF CHICAGO, ILLINOIS, ASSIGNOR TO ACIllIE STEEL COMPANY, OF

CHICAGO, ILLINOIS, A CORPORATION OF'ILLINOIS STRAP-STRETCHING DEVICE Application filed May 10, 1928. Serial No. 276,519.

This invention relates to improvements in strap stretching devices and its purpose'is toprovide improved means for stretching or drawing taut a metal strap which has been passed-around a box or other package. The principal object of the invention is to provide an improved strap stretching device adapted for use in drawing taut a flat metal strap. Another important object of the invention is to provide an improved strap stretching device in which the stretching of the strap and'the cutting off of the strap from the source of supplfyis effected by the continuing operation '0 single operating memher. A further object of the invention is to provide a simple and compact stretching device which may be conveniently operated for stretching straps around relatively small packages. Other objects relate to various features of construction and arrangement which will appear more fully hereinafter.

The nature of the invention will be understood from the following specification taken with the accompanying drawings in which one embodiment is illustrated. In the draw ings, Figure 1 shows a front elevation of the improved strap stretching device applied to the top surface of a box about which a strap has been passed and connected to the stretching device preliminary to the stretching thereof;

Fig. 2 is a front elevation of the box and strap stretching device, similar to that of Fig. 1, with a portion of the handle removed, illustrating the relative positions of the parts after the strap has been drawn taut around the box and a seal applied to the overlapping ends for securing'the strap in that condition; v

Fig. 3 is a top plan view of the improved "strap stretching device illustrated'in Figs.

1 and 2;

Fig. 4 shows a side elevation of the improved strap stretching device, and,

Fig. 5 is a perspective view of the cam by which the stretching mechanism is operated.

The strap stretching device illustrated in the drawings comprises a flat base plate adapted to rest upon the top surface of the box or package 11 about which the flat steel strap 12 is adapted to be passed as illustrated drawn as successive boxes or pac ages are reinforced by the application of straps there,- to. After being passed around the box, the free end of the strap.12 is carried over a stationary gripping plate 13 which is formed as a forward projection of the plate 10 and which has a top surface beveled at the edges as shown at 13". 12, when located on the stationary gripping plate 13, lies beneath the lower extremity of the gripping dog 14, having a serrated lower surface 14 adapted to engage'and grip the upper side of the strap; This gripping dog is pivotally mounted on a pin 15 which is secured stationarily, in a boss 16, carried by the plate 10 and a coil sprin 17- mounted on the outer end of the" pin 15 a jacent the enlarged head 15 "thereof, has itscnds connected to the pin and to the gripping dog 14in such a manner that this gripping dog is normally forced downwardly into engagement with the strap. The gripping dog 14 is adapted to be swung away from the strap 12 by means of the handle 14 and the limit of this swingin movement is determined by the stationary cutting die 18 which is secured on the plate ,10 and which has its forward end spaced upwardly therefrom forming a slot 19 through which the strap 12 passes, the free end 12 of the strap projecting across an opening 20 where the overlappin ends of the strap are brought together and w ere the seal is applied to the strap as hereinafter described.

After the free end of the strap is secured beneath the gripping device 14 with the extremity thereof pro ecting across the opening 20, the strap is carried around the box 11 and it is passed over a movable gripping.

plate 21 which is adapted to slide inwardly over a thin plate 22 in the direction indicated by the arrow 23,.the plate. 22 being attached to or forming a forward projection of the base plate 10. At the edge of the plate 22 adjacent the opening 20, there is provided a bar 24 over which the strap 12 passes and The free end of the strap this bar is preferably formed as an integral 1nto engagement with the top surface of the strap. The gripping dog may be swung away from the strap-by means of the handle It will be noted that the handles 14 and 25 are curved laterally away from the central part of the stretching device and that the lower gripping portions of these dogs are inclined downwardly and inwardly toward the vertical center line of the opening 20, so that when the movable gripping plate 21 and the dog 25 are moved inwardly toward the opening 20 to stretch the strap, as herein after described, the tension set up in the strap tends automatically to cause both of the dogs 14 and 25 to increase their grip on the strap.

The movement-of the movable gripping plate 21 and its gripping dog 25 is effected by means of a transverse actuating bar 30 with which the plate 21 is preferably integrally formed. The bar 30 slides between a guide flange 31 formed on the upper side of the plate 10 and a guide member 32 which is secured to the upper side of the forward extension 24 of the plate 10 and the bar 30 is further guided by the rear end of the cutting 'die 18 which is secured to the stationary gripping plate 13 by means of the rivet 33. The bar 30 is maintained in its guideway by means of the cover plate 34 which is detachably secured in position by means of the screws 35. The'bar '30 is actuated by a lever 37 with which it is pivotally connected by a pin 38. The rear end of the lever 37 engages a horizontal' slot in a guide member 39 and is provided with a curved surface 40 adapted to bear against a shoulder 41 at the inner end of the slot in the member 39 so that the curved surface 40 is adapted to rock on the shoulder 41 when the lever 37 is actuated to effect movement of the bar 30. The lever 37 is normally actuated to move toward the position illustrated in Figs. 1 and 3 by means of coil springs 42 and 43 which engage apertures 4 in the lever and which are passed aroun studs 45 mounted in the pin. Additional holes 46 are provided in the lever 37 and other studs 47 are mounted on the plate 10 so that additional springs may be provided for in creasing the resistance which must be overcome in stretching the strap and for effecting a corresponding increase in the force tending to return the lever 37 to the position illustrated in Fig. 3.

The actuation of the lever- 37 is brought about by a rotatable cam 50 having the form illustrated particularly in Fig. 5. The cam 50 comprises a circular plate 51 having projecting from its central part a hollow shaft 52 which is journaled in a pair of bearing plates v 53 extending upwardly from a bearing block attached to the plate 10. The shaft 52 is internally threaded and is engaged by a screw 54 the head of which seats against a washer 55. Between the bearing plates 53 there is mounted the hub 56 of a hand lever or operating member 56 having a transverse handle 56" at the outer end thereof. This lever 56 is rotatably mounted on the shaft 52 of the cam 50 and it is adaptedto effect the rotation of the cam through a pawl 58 which is pivotally mounted on a pin 59 carried by the hand lever 56 andwhich is normally actuated to engage the peripheral surface of the cam by means of a coil spring 60. The cam 50 is provided on, itsvcircular peripheral surface 61 with a pair ofnotches 62 adapted to be engaged by the pawl 58 and these notches are of such form that the cam is rotated when the handle 56 is swung upwardly and forwardly toward the opening 20 in the base plate 10. The cam 50 is provided with an annular laterally projecting flange 63 of varying width provided on its surface with two similar inclined cam surfaces 64 each of which terminates at one end in a shoulder 65 extending substantially parallel to the axis of rotation of the cam. The other end of each cam surface 64 terminates in a surface 66 which is substantially perpendicular to the axis of rotation of the caml The cam surfaces 64 serve to actuate the lever 37 through a roller 63 which is rotatablymounted on a pin69 secured to an intermediate part of the lever 37. Vhen the pawl 58 is in engagement with one of the notches 62 as shown in Fig. 3, the upward and forward movement of the hand lever 56 causes the cam 50 to rotate in the direction indicated by the arrow in Fig. 4 with the result that the roller 68 rides on the inclined cam surface 64 shown in Fig. 3 and thus moves the lever 37 toward the right as viewed in Fig. 3, with the result that the bar 30 and the movable gripping plate 21 are carried inwardly in a corresponding direction, thereby stretching the strap which is held by the gripping dog. As the strap is stretched, the supply end 12* thereof rides over the cut ting die 18.and through the-groove 14 in the gripping dog 14-until a position is reached wherein the strapis stretched taut around the package as shown in Fig. 2 and the movable gripping plate 21 has moved to a position alongside the bar 24. As the parts approach this limiting position, corresponding to the stretched condition of the strap, the portion 12 of the strap which overlies the extremity 12 is severed from the supply portion 12 by the action of a cutting blade 71 which is secured within a flange 72 formed on the operating handle 56 by means of a screw 73. This blade 71 has an inclined cutting edge 71 terminating in a shoulder 71", this shoulder being provided to prevent sidewise movement of the strap when it is engaged by the inclined cutting blade. The blade 71 cooperates with the cutting die 18 which has a cutting edge 18" and which has its adjacent face 18 inclined inwardly as shownin Figs. 1 and 2. As the parts reach the position shown in Fig. 2, the strap is cut off and the parts 12 is forced downwardly into overlapping relation with the part 12 over the opening 20 which is formed in the forward end ofthe base plate 10 so that the parts of the strap are thus overlapped in position to be united by a seal. A lug 75 on the under side of the lever 56 is adapted to engage the side of a block 76, secured on the bar 24, to maintain a close engagement of the cutting blade and the cutting die. The operating andle 56 is then returned. When the operating lever 56 is in this forward position illustrated in Fig. 2, the roller 68 carried by the lever 37 has passed into engagement with the surface 66 at the outer end of one of the cam surfaces 64 so that the lever 37 is then held in its proper position to maintain the strap in its. taut condition. While the strap is thus held, the operating lever 56 is returned to the position illustrated in Fig. 3, which is permitted by the sliding of the pawl 58 out of engagement with the notch 62 previously engaged thereby, and, with the lever 56 out of the way, the operator can then apply a seal to the overlapping ends of the strap, as shown by dotted lines at 85in Fig. 2. After the seal has been applied to secure the ends of the strap together, the operator makes a X slight forward movement of the operating handle 56 from the rear position illustrated in Fig. 3 and, the pawl 58 being then in engagement with the other notch 62 in the cam 50, the cam is rotated sufiiciently to cause the roller 68 to ride off of the surface 66 engaged thereby and to fall into position at the bottom of the next adjacent cam surface 64 in contact with the surface 65 at the end of that cam surface. As soon as the roller 68 passes into that inner position adjacent the surface 65, the springs 42- and 43 automatically accomplish, in addition, the movement of the bar 30 and the corresponding return movement of the movable gripping plate 21 to the position illustrated in Fig. 1. This return movement is permitted by reason of the fact that the inclination of the dog 25 is-such as to allow this dog to slide over the surface of the strap when the gripping plate 21 is moved toward the left as viewed in Figs. 1 and 2. The strap may be released from the dogs by sliding the base plate 10 from position beneath the strap. The strap will then be under suflicient tension to spring downwardly into contact with the surface of the box or package 11 and the strap stretching device will be in readiness for application to another strap on the same or another box.

While one form of the invention has been shown and described by way of illustration,

it will be understood that it may be constructadapted to effect a plurality of similar operations of said actuating means upon each rotation thereof.

2. The combination in a strap stretching device of a pair of devices each adapted to grip one end portion of a strap looped around a package, actuating means for moving said,

gripping devices toward each other to stretch the strap taut around the package, and means comprising a handle movable transversely to the path of relative movement of said gripping devices for effecting operation of said actuating means and for cutting off the strap.

3. The combination in a strap stretching device of a pair of relatively movable devices adapted to grip a portion of a strap, actuating means for effecting said relative movement of said gripping devices, a rotatable cam having a plurality of inclined cam surfaces for actuating said actuating mechanism, and reciprocating means adapted upon operation thereof to effect apartial rotation of said cam.

4. The combination in a, strap stretching device of a pair of relatively movable devices adapted to grip a portion of a strap, actuating means for effecting said relative movement of said gripping devices, a rotatable cam having a plurality of inclined cam surfaces for actuating said actuating mechanism, an operating lever, and a pawl carried by said lever and engaging said cam for effecting rotation thereof by the movement of said lever.

5. The combination in a strap stretching device of a pair of gripping devices movable toward each other for stretching a strap, a lever having a pivotal connection with one of said gripping devices, means engaging said lever for normally effecting separation of said grippin devices, and manually operated means for efiecting movement of said gripping devices toward each other.

6. The combination in a strap stretching device of a pair of gripping devices movable toward each other for stretching a strap, a lever having a pivotal connection with one of said gripping devices, means engaging said lever for normally effecting separation of said gripping devices, and means arranged III to operate said lever to stretch said strap and then to release said strap and permit the separation of said gripping devices.

7. The combination in a strap stretching device of a pair of relatively movable gripping devices adapted to stretch the strap upon movement toward each other, actuating means for effecting said relative movement toward each other of said gripping devices, and means including a cam for operating said actuating means, said cam being mounted for rotation and having an inclined cam surface directed at an angle to its axis of rotation and terminating in a part extending substantially normal to said axis of rotation.

8. The combination in a strap stretching device of a pair of relatively movable gripping devices, a lever adapted to effect said relative movement, a rotatable cam, a roller mounted on said lever, resilient means tending to maintain said roller in contact with said cam, said cam having a plurality of successive inclined cam surfaces adapted to coact with said roller, and means for rotating said cam.

9. The combination in a strap stretching device of a pair of relatively movable gripping devices, a lever adapted to effect said relative movement, a rotatable cam, a roller mounted on said lever, resilient means tending to maintain said roller in contact with said cam, said cam having a plurality of successive inclined cam surfaces adapted to coact with said roller, and reciprocating means adapted upon each actuation thereof to effect rotation of said cam through an angular dis-- tance corresponding to one of said inclined cam surfaces.

10. The combination in a strap stretching device of a pair of relatively movable strap gripping devices, a lever adapted to effect said relative movement, said lever having a curved bearing surface, a stationary part engaging said surface, resilient means connected to said lever and tending normally to effect separation of said gripping devices, a rotatable cam to efl'ectmovement of said lever in opposition to said resilient means, and means for effecting rotation of said cam.

11. The combination in a strap stretching device of a horizontal base plate, a stationary gripping plate carried by said base plate, a relatively movable gripping plate mounted for movement on said base plate, a gripping dog adapted to cooperate with each said gripping plate, a horizontal lever pivotally mounted on said base plate and having a pivotal connection with said movable grip ing plate, a cam rotatably mounted on said ase plate, a member carried by said lever for engaging said cam, resilient means tending normally to maintain said member in contact with said cam, and means for efiecting rotation of said cam.

12. The combination in a strap stretching device of a horizontal base plate, a stationary gripping plate carried by said base plate, a relatively movable gripping plate mounted for movement on said base plate, a grippin dog adapted to cooperate with each of sai gripping plates, a horizontal lever pivotally mounted on said base plate and having a pivotal connection with said movable gripping plate, a cam rotatably mounted on said base plate, a member carried by said lever for engaging said cam, resilient means tending normally to maintain said member in contact with said cam, a reciprocating lever mounted for pivotal movement about the axis of rotation of said cam, and a pawl carried by said lever, said cam having notchesto be engaged by said pawl.

13. The combination in a strap stretching device of a pair of relatively movable gripping plates, a gripping dog carried by one of said plates to grip the free end of a strap, another gripping dog carried by the other of said plates to grip a portion of the strap leading from a source of supply,.said first named gripping dog having a notch through which said supply portion of said strap extends, and means for effecting movement of said plates toward each other to effect the stretching of the strap.

14. The combination in a strap stretching device of a pair of relatively movable gripping plates, a gripping dog pivotally mounted on each of said plates, said gripping dogs converging downwardly and inwardly from their pivotal axes, one of said gripping dogs having a notch therein. said last mentioned gripping dog being adapted to engage a strap adjacent its free end and to grip the same in cooperation with its gripping plate, the other of said gripping dogs and its grippingplate being adapted to grip the supply portion of said strap after it has been passe around the package, the portion of the strap leading from the source of supply extending through said notch in said first named gripping dog, and means for effecting relative movement of said gripping plates toward each other to effect the stretching of the strap.

15. The combination in a strap stretching device of a pair of relatively movable gripping plates, a gripping dog pivotally mounted on each of said plates, said gripping dogs converging downwardly and inwardly from their pivotal axes, one of said gripping dogs having a notch therein, said last mentioned gripping dog being adapted to engage a strap adjacent its free end and to grip the same in cooperation with its gripping plate, the other of said gripping dogs and its gripping plate being adapted to grip the supply portion of said strap after it has been passed around the package, the portion of the strap leading from the source of supply extending through said notch in said first named gripping dog, means for effecting relative movement of said gripping plates toward each other to effect the stretching of the strap. and means actuated by the continued operation of said last named means for severing the strap from the source of supply.

16. The combination in a strap stretching device of a pair of strap gripping devices movable toward each other for efl'ecting the stretching of a strap looped around a package, actuating means for effecting said relative movement of said gripping devices, an operating lever movable transversely to the direction of relative movement of said gripping devices for operating said actuating means, and means actuated by said lever for severing the strap from the source of supply.

17. The combination in a strap stretching device of a pair of relatively movable gripping devices each adapted to grip a portion of a strap leading from a source of supply and looped around the package, actuating mechanism for effecting relative movement of said gripping devices to stretch said strap, and an operating lever adapted upon its initial movement to effect said relative movement of said gripping devices to render the strap taut and adapted upon further movement thereof to sever the strap from the source of supply to leave the ends thereof overlapping.

18. The combination in a strap stretching device of a base plate having an opening at its forward end, a stationary gripping plate mounted at one side of said opening, a movable gripping plate mounted at the other side of said opening, a gripping dog cooperating with each of said gripping plates to grip a portion of a strap leading from a source of supply and looped around the package, actuating mechanism carried by said base plate for effecting relative movement of said gripping plates and their gripping dogs for stretching said strap, a cutting die mounted on said base plate adjacent said opening, an operating lever for said actuating mechanism, and a cutting blade mounted on said lever to cooperate with said cutting die, said lever being adapted upon its initial movement to effect the operation of said actuating mechanism to stretch said strap taut and being adapted upon the final movement thereof to bring said cutting blade into cooperation with said cutting die to sever said strap from its source of supply.

19. The combination in a strap stretching device of a base plate having an opening at its forward end, a stationary gripping plate mounted at one side of said opening, a movable gripping plate mounted at the other side of said opening, a gripping dog cooperating with each of said gripping plates to grip a portion of a strap leading from a source of supply and looped around the package, actuating mechanism carried by said base plate for effecting relative movement of said gripping plates and their gripping dogs for stretching said strap, a cutting die mounted on said base plate adjacent said opening, an operating lever for said actuating mechanism, a cutting blade mounted on said lever to cooperate with said cutting die, said lever being adapted upon its initial moveto effect the operation of said actuating mechanism to stretch said strap taut and being adapted upon the final movement thereof to bring said cutting blade into cooperation with said cutting die to sever said strap from its source of supply, and means carried by said base plate and said lever for preventing movement of said cutting blade away from said cutting die during the operation of severing said strap.

20. The combination in a strap stretching device, of a horizontal base plate, a pair of relatively movable gripping plates carried by said base plate, a pair of gripping dogs each pivotally mounted adjacent one of said gripping plates and having a gripping part adapted to cooperate with its plate to grip a strap looped around a package, said gripping dogs being inclined inwardly toward each other from their pivotal axes and being adapted to have relative movement toward each other to effect the stretching of said strap, and means comprising a lever movable transversely to the path of movement of said gripping dogs for effecting said relative movement.

21. The combination in a strap stretching device, of a horizontal base plate, a pair of relatively movable gripping plates carried by said base plate, a pair of gripping dogs each pivotally mounted adjacent one of said gripping plates and having a. gripping part adapted to cooperate with its plate to grip a strap looped around a package, said gripping dogs being inclined inwardly toward each other from their pivotal axes and being adapted to have relative movement toward each other to effect the stretching of said strap, means comprising a lever connected to one of said gripping plates for eflecting said relative movement of said gripping plates and gripping dogs, and means comprising a cam rotatable about an axis extending parallel to the path of relative movement of said gripping plates for efl'ecting said relative movement.

In testimony whereof, I have subscribed my name.

RALPH H. NORTON. 

